// Copyright Epic Games, Inc. All Rights Reserved. #include "RenderGraphValidation.h" #include "RenderGraphPrivate.h" #include "Misc/FileHelper.h" #include "Misc/Paths.h" #include "MultiGPU.h" #if RDG_ENABLE_DEBUG namespace { template void EnumerateSubresources(const FRHITransitionInfo& Transition, uint32 NumMips, uint32 NumArraySlices, uint32 NumPlaneSlices, TFunction Function) { uint32 MinMipIndex = 0; uint32 MaxMipIndex = NumMips; uint32 MinArraySlice = 0; uint32 MaxArraySlice = NumArraySlices; uint32 MinPlaneSlice = 0; uint32 MaxPlaneSlice = NumPlaneSlices; if (!Transition.IsAllMips()) { MinMipIndex = Transition.MipIndex; MaxMipIndex = MinMipIndex + 1; } if (!Transition.IsAllArraySlices()) { MinArraySlice = Transition.ArraySlice; MaxArraySlice = MinArraySlice + 1; } if (!Transition.IsAllPlaneSlices()) { MinPlaneSlice = Transition.PlaneSlice; MaxPlaneSlice = MinPlaneSlice + 1; } for (uint32 PlaneSlice = MinPlaneSlice; PlaneSlice < MaxPlaneSlice; ++PlaneSlice) { for (uint32 ArraySlice = MinArraySlice; ArraySlice < MaxArraySlice; ++ArraySlice) { for (uint32 MipIndex = MinMipIndex; MipIndex < MaxMipIndex; ++MipIndex) { Function(FRDGTextureSubresource(MipIndex, ArraySlice, PlaneSlice)); } } } } const ERHIAccess AccessMaskCopy = ERHIAccess::CopySrc | ERHIAccess::CopyDest | ERHIAccess::CPURead; const ERHIAccess AccessMaskCompute = ERHIAccess::SRVCompute | ERHIAccess::UAVCompute; const ERHIAccess AccessMaskRaster = ERHIAccess::ResolveSrc | ERHIAccess::ResolveDst | ERHIAccess::DSVRead | ERHIAccess::DSVWrite | ERHIAccess::RTV | ERHIAccess::SRVGraphics | ERHIAccess::UAVGraphics | ERHIAccess::Present | ERHIAccess::VertexOrIndexBuffer; const ERHIAccess AccessMaskComputeOrRaster = ERHIAccess::IndirectArgs; /** Validates that we are only executing a single render graph instance in the callstack. Used to catch if a * user creates a second FRDGBuilder instance inside of a pass that is executing. */ bool GRDGInExecutePassScope = false; } //! namespace FRDGUserValidation::FRDGUserValidation() : ExpectedNumMarks(FMemStack::Get().GetNumMarks()) {} FRDGUserValidation::~FRDGUserValidation() { checkf(bHasExecuted, TEXT("Render graph execution is required to ensure consistency with immediate mode.")); } void FRDGUserValidation::MemStackGuard() { checkf(ExpectedNumMarks == FMemStack::Get().GetNumMarks(), TEXT("A MemStack mark was added during the FRDGBuilder lifetime. This is not allowed as it will free memory still used by the builder.")); } void FRDGUserValidation::ExecuteGuard(const TCHAR* Operation, const TCHAR* ResourceName) { checkf(!bHasExecuted, TEXT("Render graph operation '%s' with resource '%s' must be performed prior to graph execution."), Operation, ResourceName); MemStackGuard(); } void FRDGUserValidation::ValidateCreateTexture(FRDGTextureRef Texture) { MemStackGuard(); check(Texture); if (GRDGDebug) { TrackedTextures.Add(Texture); } } void FRDGUserValidation::ValidateCreateBuffer(FRDGBufferRef Buffer) { MemStackGuard(); check(Buffer); if (GRDGDebug) { TrackedBuffers.Add(Buffer); } } void FRDGUserValidation::ValidateCreateExternalTexture(FRDGTextureRef Texture) { ValidateCreateTexture(Texture); Texture->ParentDebugData.bHasBeenProduced = true; } void FRDGUserValidation::ValidateCreateExternalBuffer(FRDGBufferRef Buffer) { ValidateCreateBuffer(Buffer); Buffer->ParentDebugData.bHasBeenProduced = true; } void FRDGUserValidation::ValidateExtractResource(FRDGParentResourceRef Resource) { MemStackGuard(); check(Resource); checkf(Resource->ParentDebugData.bHasBeenProduced, TEXT("Unable to queue the extraction of the resource %s because it has not been produced by any pass."), Resource->Name); /** Increment pass access counts for externally registered buffers and textures to avoid * emitting a 'produced but never used' warning. We don't have the history of registered * resources to be able to emit a proper warning. */ Resource->ParentDebugData.PassAccessCount++; } void FRDGUserValidation::RemoveUnusedWarning(FRDGParentResourceRef Resource) { MemStackGuard(); check(Resource); // Removes 'produced but not used' warning. Resource->ParentDebugData.PassAccessCount++; // Removes 'not used' warning. Resource->DebugData.bIsActuallyUsedByPass = true; } bool FRDGUserValidation::TryMarkForClobber(FRDGParentResourceRef Resource) const { const bool bClobber = !Resource->ParentDebugData.bHasBeenClobbered && !Resource->bExternal && IsDebugAllowedForResource(Resource->Name); if (bClobber) { Resource->ParentDebugData.bHasBeenClobbered = true; } return bClobber; } void FRDGUserValidation::ValidateAddPass(const FRDGPass* Pass, bool bSkipPassAccessMarking) { MemStackGuard(); const FRenderTargetBindingSlots* RenderTargetBindingSlots = nullptr; // Pass flags are validated as early as possible by the builder in AddPass. const ERDGPassFlags PassFlags = Pass->GetFlags(); const FRDGParameterStruct PassParameters = Pass->GetParameters(); const TCHAR* PassName = Pass->GetName(); const bool bIsRaster = EnumHasAnyFlags(PassFlags, ERDGPassFlags::Raster); const bool bIsCopy = EnumHasAnyFlags(PassFlags, ERDGPassFlags::Copy); const bool bIsAnyCompute = EnumHasAnyFlags(PassFlags, ERDGPassFlags::Compute | ERDGPassFlags::AsyncCompute); const bool bSkipRenderPass = EnumHasAnyFlags(PassFlags, ERDGPassFlags::SkipRenderPass); const auto MarkAsProduced = [&] (FRDGParentResourceRef Resource) { if (!bSkipPassAccessMarking) { auto& Debug = Resource->ParentDebugData; if (!Debug.bHasBeenProduced) { Debug.bHasBeenProduced = true; Debug.FirstProducer = Pass; } Debug.PassAccessCount++; } }; const auto MarkAsConsumed = [&] (FRDGParentResourceRef Resource) { auto& Debug = Resource->ParentDebugData; ensureMsgf(Debug.bHasBeenProduced, TEXT("Pass %s has a read dependency on %s, but it was never written to."), PassName, Resource->Name); if (!bSkipPassAccessMarking) { Debug.PassAccessCount++; } }; const auto CheckNotPassthrough = [&](FRDGResourceRef Resource) { checkf(!Resource->IsPassthrough(), TEXT("Resource '%s' was created as a passthrough resource but is attached to pass '%s'."), Resource->Name, Pass->GetName()); }; const auto CheckNotCopy = [&](FRDGResourceRef Resource) { ensureMsgf(!bIsCopy, TEXT("Pass %s, parameter %s is valid for Raster or (Async)Compute, but the pass is a Copy pass."), PassName, Resource->Name); }; bool bCanProduce = false; PassParameters.Enumerate([&](FRDGParameter Parameter) { if (Parameter.IsParentResource()) { if (FRDGParentResourceRef Resource = Parameter.GetAsParentResource()) { CheckNotPassthrough(Resource); } } else if (Parameter.IsView()) { if (FRDGViewRef View = Parameter.GetAsView()) { CheckNotPassthrough(View); CheckNotPassthrough(View->GetParent()); } } switch (Parameter.GetType()) { case UBMT_RDG_TEXTURE: { if (FRDGTextureRef Texture = Parameter.GetAsTexture()) { MarkAsConsumed(Texture); } } break; case UBMT_RDG_TEXTURE_SRV: { if (FRDGTextureSRVRef SRV = Parameter.GetAsTextureSRV()) { FRDGTextureRef Texture = SRV->GetParent(); CheckNotCopy(Texture); MarkAsConsumed(Texture); } } break; case UBMT_RDG_TEXTURE_UAV: { bCanProduce = true; if (FRDGTextureUAVRef UAV = Parameter.GetAsTextureUAV()) { FRDGTextureRef Texture = UAV->GetParent(); CheckNotCopy(Texture); MarkAsProduced(Texture); } } break; case UBMT_RDG_BUFFER: { if (FRDGBufferRef Buffer = Parameter.GetAsBuffer()) { MarkAsConsumed(Buffer); } } break; case UBMT_RDG_BUFFER_SRV: { if (FRDGBufferSRVRef SRV = Parameter.GetAsBufferSRV()) { FRDGBufferRef Buffer = SRV->GetParent(); CheckNotCopy(Buffer); MarkAsConsumed(Buffer); } } break; case UBMT_RDG_BUFFER_UAV: { bCanProduce = true; if (FRDGBufferUAVRef UAV = Parameter.GetAsBufferUAV()) { FRDGBufferRef Buffer = UAV->GetParent(); CheckNotCopy(Buffer); MarkAsProduced(Buffer); } } break; case UBMT_RDG_TEXTURE_ACCESS: { const FRDGTextureAccess TextureAccess = Parameter.GetAsTextureAccess(); const ERHIAccess Access = TextureAccess.GetAccess(); const bool bIsWriteAccess = IsWritableAccess(Access); bCanProduce |= bIsWriteAccess; if (FRDGTextureRef Texture = TextureAccess.GetTexture()) { checkf(bIsCopy || !EnumHasAnyFlags(Access, AccessMaskCopy), TEXT("Pass '%s' uses texture '%s' with access '%s' containing states which require the 'ERDGPass::Copy' flag."), Pass->GetName(), Texture->Name, *GetRHIAccessName(Access)); checkf(bIsAnyCompute || !EnumHasAnyFlags(Access, AccessMaskCompute), TEXT("Pass '%s' uses texture '%s' with access '%s' containing states which require the 'ERDGPass::Compute' or 'ERDGPassFlags::AsyncCompute' flag."), Pass->GetName(), Texture->Name, *GetRHIAccessName(Access)); checkf(bIsRaster || !EnumHasAnyFlags(Access, AccessMaskRaster), TEXT("Pass '%s' uses texture '%s' with access '%s' containing states which require the 'ERDGPass::Raster' flag."), Pass->GetName(), Texture->Name, *GetRHIAccessName(Access)); checkf(bIsAnyCompute || bIsRaster || !EnumHasAnyFlags(Access, AccessMaskComputeOrRaster), TEXT("Pass '%s' uses texture '%s' with access '%s' containing states which require the 'ERDGPassFlags::Compute' or 'ERDGPassFlags::AsyncCompute' or 'ERDGPass::Raster' flag."), Pass->GetName(), Texture->Name, *GetRHIAccessName(Access)); if (bIsWriteAccess) { MarkAsProduced(Texture); } } } break; case UBMT_RDG_BUFFER_ACCESS: { const FRDGBufferAccess BufferAccess = Parameter.GetAsBufferAccess(); const ERHIAccess Access = BufferAccess.GetAccess(); const bool bIsWriteAccess = IsWritableAccess(Access); bCanProduce |= bIsWriteAccess; if (FRDGBufferRef Buffer = BufferAccess.GetBuffer()) { checkf(bIsCopy || !EnumHasAnyFlags(Access, AccessMaskCopy), TEXT("Pass '%s' uses buffer '%s' with access '%s' containing states which require the 'ERDGPass::Copy' flag."), Pass->GetName(), Buffer->Name, *GetRHIAccessName(Access)); checkf(bIsAnyCompute || !EnumHasAnyFlags(Access, AccessMaskCompute), TEXT("Pass '%s' uses buffer '%s' with access '%s' containing states which require the 'ERDGPass::Compute' or 'ERDGPassFlags::AsyncCompute' flag."), Pass->GetName(), Buffer->Name, *GetRHIAccessName(Access)); checkf(bIsRaster || !EnumHasAnyFlags(Access, AccessMaskRaster), TEXT("Pass '%s' uses buffer '%s' with access '%s' containing states which require the 'ERDGPass::Raster' flag."), Pass->GetName(), Buffer->Name, *GetRHIAccessName(Access)); checkf(bIsAnyCompute || bIsRaster || !EnumHasAnyFlags(Access, AccessMaskComputeOrRaster), TEXT("Pass '%s' uses buffer '%s' with access '%s' containing states which require the 'ERDGPassFlags::Compute' or 'ERDGPassFlags::AsyncCompute' or 'ERDGPass::Raster' flag."), Pass->GetName(), Buffer->Name, *GetRHIAccessName(Access)); if (IsWritableAccess(BufferAccess.GetAccess())) { MarkAsProduced(Buffer); } } } break; case UBMT_RENDER_TARGET_BINDING_SLOTS: { RenderTargetBindingSlots = &Parameter.GetAsRenderTargetBindingSlots(); bCanProduce = true; } break; } }); checkf(bCanProduce || EnumHasAnyFlags(PassFlags, ERDGPassFlags::NeverCull) || PassParameters.HasExternalOutputs(), TEXT("Pass '%s' has no graph parameters defined on its parameter struct and did not specify 'NeverCull'. The pass will always be culled."), PassName); /** Validate that raster passes have render target binding slots and compute passes don't. */ if (RenderTargetBindingSlots) { checkf(bIsRaster, TEXT("Pass '%s' has render target binding slots but is not set to 'Raster'."), PassName); } else { checkf(!bIsRaster || bSkipRenderPass, TEXT("Pass '%s' is set to 'Raster' but is missing render target binding slots. Use 'SkipRenderPass' if this is desired."), PassName); } /** Validate render target / depth stencil binding usage. */ if (RenderTargetBindingSlots) { const auto& RenderTargets = RenderTargetBindingSlots->Output; { const auto& DepthStencil = RenderTargetBindingSlots->DepthStencil; const auto CheckDepthStencil = [&](FRDGTextureRef Texture) { // Depth stencil only supports one mip, since there isn't actually a way to select the mip level. check(Texture->Desc.NumMips == 1); CheckNotPassthrough(Texture); if (DepthStencil.GetDepthStencilAccess().IsAnyWrite()) { MarkAsProduced(Texture); } else { MarkAsConsumed(Texture); } }; FRDGTextureRef Texture = DepthStencil.GetTexture(); if (Texture) { checkf( EnumHasAnyFlags(Texture->Desc.Flags, TexCreate_DepthStencilTargetable | TexCreate_DepthStencilResolveTarget), TEXT("Pass '%s' attempted to bind texture '%s' as a depth stencil render target, but the texture has not been created with TexCreate_DepthStencilTargetable."), PassName, Texture->Name); CheckDepthStencil(Texture); } } const uint32 RenderTargetCount = RenderTargets.Num(); { /** Tracks the number of contiguous, non-null textures in the render target output array. */ uint32 ValidRenderTargetCount = 0; for (uint32 RenderTargetIndex = 0; RenderTargetIndex < RenderTargetCount; ++RenderTargetIndex) { const FRenderTargetBinding& RenderTarget = RenderTargets[RenderTargetIndex]; FRDGTextureRef Texture = RenderTarget.GetTexture(); FRDGTextureRef ResolveTexture = RenderTarget.GetResolveTexture(); if (ResolveTexture && ResolveTexture != Texture) { checkf(RenderTarget.GetTexture(), TEXT("Pass %s specified resolve target '%s' with a null render target."), PassName, ResolveTexture->Name); ensureMsgf( EnumHasAnyFlags(ResolveTexture->Desc.Flags, TexCreate_ResolveTargetable), TEXT("Pass '%s' attempted to bind texture '%s' as a render target, but the texture has not been created with TexCreate_ResolveTargetable."), PassName, ResolveTexture->Name); CheckNotPassthrough(ResolveTexture); MarkAsProduced(ResolveTexture); } if (Texture) { ensureMsgf( EnumHasAnyFlags(Texture->Desc.Flags, TexCreate_RenderTargetable | TexCreate_ResolveTargetable), TEXT("Pass '%s' attempted to bind texture '%s' as a render target, but the texture has not been created with TexCreate_RenderTargetable."), PassName, Texture->Name); CheckNotPassthrough(Texture); const bool bIsLoadAction = RenderTarget.GetLoadAction() == ERenderTargetLoadAction::ELoad; /** Validate that load action is correct. We can only load contents if a pass previously produced something. */ { const bool bIsLoadActionInvalid = bIsLoadAction && !Texture->ParentDebugData.bHasBeenProduced; checkf( !bIsLoadActionInvalid, TEXT("Pass '%s' attempted to bind texture '%s' as a render target with the 'Load' action specified, but the texture has not been produced yet. The render target must use either 'Clear' or 'NoAction' action instead."), PassName, Texture->Name); } /** Validate that any previously produced texture contents are loaded. This occurs if the user failed to specify a load action * on a texture that was produced by a previous pass, effectively losing that data. This can also happen if the user 're-uses' * a texture for some other purpose. The latter is considered bad practice, since it increases memory pressure on the render * target pool. Instead, the user should create a new texture instance. An exception to this rule are untracked render targets, * which are not actually managed by the render target pool and likely represent the frame buffer. */ { // Ignore external textures which are always marked as produced. We don't need to enforce this warning on them. const bool bHasBeenProduced = Texture->ParentDebugData.bHasBeenProduced && !Texture->bExternal; // We only validate single-mip textures since we don't track production at the subresource level. const bool bFailedToLoadProducedContent = !bIsLoadAction && bHasBeenProduced && Texture->Desc.NumMips == 1; // Untracked render targets aren't actually managed by the render target pool. const bool bIsUntrackedRenderTarget = Texture->PooledRenderTarget && !Texture->PooledRenderTarget->IsTracked(); // In multi-gpu, when running with "r.EnableMultiGPUForkAndJoin", it's possible for each GPU to clear the same RT in turn. // When this happens, they are not actually working on the same resource, see for example the implementation of FD3D12MultiNodeGPUObject. ensureMsgf((!bFailedToLoadProducedContent || bIsUntrackedRenderTarget) || (GNumExplicitGPUsForRendering > 1 && RenderTarget.GetLoadAction() == ERenderTargetLoadAction::EClear), TEXT("Pass '%s' attempted to bind texture '%s' as a render target without the 'Load' action specified, despite a prior pass having produced it. It's invalid to completely clobber the contents of a resource. Create a new texture instance instead."), PassName, Texture->Name); } /** Mark the pass as a producer for render targets with a store action. */ MarkAsProduced(Texture); } else { /** Found end of contiguous interval of valid render targets. */ ValidRenderTargetCount = RenderTargetIndex; break; } } /** Validate that no holes exist in the render target output array. Render targets must be bound contiguously. */ for (uint32 RenderTargetIndex = ValidRenderTargetCount; RenderTargetIndex < RenderTargetCount; ++RenderTargetIndex) { const FRenderTargetBinding& RenderTarget = RenderTargets[RenderTargetIndex]; checkf(RenderTarget.GetTexture() == nullptr && RenderTarget.GetResolveTexture() == nullptr, TEXT("Render targets must be packed. No empty spaces in the array.")); } } } } void FRDGUserValidation::ValidateExecuteBegin() { MemStackGuard(); checkf(!bHasExecuted, TEXT("Render graph execution should only happen once to ensure consistency with immediate mode.")); } void FRDGUserValidation::ValidateExecuteEnd() { MemStackGuard(); bHasExecuted = true; if (GRDGDebug) { auto ValidateResourceAtExecuteEnd = [](const FRDGParentResourceRef Resource) { check(Resource->ReferenceCount == 0); const auto& ParentDebugData = Resource->ParentDebugData; const bool bProducedButNeverUsed = ParentDebugData.PassAccessCount == 1 && ParentDebugData.FirstProducer; if (bProducedButNeverUsed) { check(ParentDebugData.bHasBeenProduced); EmitRDGWarningf( TEXT("Resource %s has been produced by the pass %s, but never used by another pass."), Resource->Name, ParentDebugData.FirstProducer->GetName()); } }; for (const FRDGTextureRef Texture : TrackedTextures) { ValidateResourceAtExecuteEnd(Texture); const bool bHasBeenProducedByGraph = !Texture->bExternal && Texture->ParentDebugData.PassAccessCount > 0; if (bHasBeenProducedByGraph && !Texture->TextureDebugData.bHasNeededUAV && EnumHasAnyFlags(Texture->Desc.Flags, TexCreate_UAV)) { EmitRDGWarningf( TEXT("Resource %s first produced by the pass %s had the TexCreate_UAV flag, but no UAV has been used."), Texture->Name, Texture->ParentDebugData.FirstProducer->GetName()); } if (bHasBeenProducedByGraph && !Texture->TextureDebugData.bHasBeenBoundAsRenderTarget && EnumHasAnyFlags(Texture->Desc.Flags, TexCreate_RenderTargetable)) { EmitRDGWarningf( TEXT("Resource %s first produced by the pass %s had the TexCreate_RenderTargetable flag, but has never been bound as a render target of a pass."), Texture->Name, Texture->ParentDebugData.FirstProducer->GetName()); } } for (const FRDGBufferRef Buffer : TrackedBuffers) { ValidateResourceAtExecuteEnd(Buffer); } } TrackedTextures.Empty(); TrackedBuffers.Empty(); } void FRDGUserValidation::ValidateExecutePassBegin(const FRDGPass* Pass) { check(Pass); checkf(!GRDGInExecutePassScope, TEXT("Render graph is being executed recursively. This usually means a separate FRDGBuilder instance was created inside of an executing pass.")); GRDGInExecutePassScope = true; SetAllowRHIAccess(Pass, true); if (GRDGDebug) { Pass->GetParameters().EnumerateUniformBuffers([&](FRDGUniformBufferRef UniformBuffer) { // Global uniform buffers are always marked as used, because FShader traversal doesn't know about them. if (UniformBuffer->IsGlobal()) { UniformBuffer->MarkResourceAsUsed(); } }); Pass->GetParameters().Enumerate([&](FRDGParameter Parameter) { switch (Parameter.GetType()) { case UBMT_RDG_TEXTURE_UAV: if (FRDGTextureUAVRef UAV = Parameter.GetAsTextureUAV()) { FRDGTextureRef Texture = UAV->Desc.Texture; Texture->TextureDebugData.bHasNeededUAV = true; } break; case UBMT_RDG_TEXTURE_ACCESS: { const FRDGTextureAccess TextureAccess = Parameter.GetAsTextureAccess(); if (FRDGTextureRef Texture = TextureAccess.GetTexture()) { const ERHIAccess Access = TextureAccess.GetAccess(); if (EnumHasAnyFlags(Access, ERHIAccess::UAVMask)) { Texture->TextureDebugData.bHasNeededUAV = true; } if (EnumHasAnyFlags(Access, ERHIAccess::RTV | ERHIAccess::DSVRead | ERHIAccess::DSVWrite)) { Texture->TextureDebugData.bHasBeenBoundAsRenderTarget = true; } Texture->MarkResourceAsUsed(); } } break; case UBMT_RDG_BUFFER_ACCESS: if (FRDGBufferRef Buffer = Parameter.GetAsBuffer()) { Buffer->MarkResourceAsUsed(); } break; case UBMT_RENDER_TARGET_BINDING_SLOTS: { const FRenderTargetBindingSlots& RenderTargets = Parameter.GetAsRenderTargetBindingSlots(); RenderTargets.Enumerate([&](FRenderTargetBinding RenderTarget) { FRDGTextureRef Texture = RenderTarget.GetTexture(); Texture->TextureDebugData.bHasBeenBoundAsRenderTarget = true; Texture->MarkResourceAsUsed(); }); if (FRDGTextureRef Texture = RenderTargets.DepthStencil.GetTexture()) { Texture->TextureDebugData.bHasBeenBoundAsRenderTarget = true; Texture->MarkResourceAsUsed(); } } break; } }); } } void FRDGUserValidation::ValidateExecutePassEnd(const FRDGPass* Pass) { SetAllowRHIAccess(Pass, false); const FRDGParameterStruct PassParameters = Pass->GetParameters(); if (GRDGDebug) { uint32 TrackedResourceCount = 0; uint32 UsedResourceCount = 0; PassParameters.Enumerate([&](FRDGParameter Parameter) { if (Parameter.IsResource()) { if (FRDGResourceRef Resource = Parameter.GetAsResource()) { TrackedResourceCount++; UsedResourceCount += Resource->DebugData.bIsActuallyUsedByPass ? 1 : 0; } } }); if (TrackedResourceCount != UsedResourceCount) { FString WarningMessage = FString::Printf( TEXT("'%d' of the '%d' resources of the pass '%s' were not actually used."), TrackedResourceCount - UsedResourceCount, TrackedResourceCount, Pass->GetName()); PassParameters.Enumerate([&](FRDGParameter Parameter) { if (Parameter.IsResource()) { if (const FRDGResourceRef Resource = Parameter.GetAsResource()) { if (!Resource->DebugData.bIsActuallyUsedByPass) { WarningMessage += FString::Printf(TEXT("\n %s"), Resource->Name); } } } }); EmitRDGWarning(WarningMessage); } } PassParameters.Enumerate([&](FRDGParameter Parameter) { if (Parameter.IsResource()) { if (FRDGResourceRef Resource = Parameter.GetAsResource()) { Resource->DebugData.bIsActuallyUsedByPass = false; } } }); GRDGInExecutePassScope = false; } void FRDGUserValidation::SetAllowRHIAccess(const FRDGPass* Pass, bool bAllowAccess) { Pass->GetParameters().Enumerate([&](FRDGParameter Parameter) { if (Parameter.IsResource()) { if (FRDGResourceRef Resource = Parameter.GetAsResource()) { Resource->DebugData.bAllowRHIAccess = bAllowAccess; } } else if (Parameter.IsRenderTargetBindingSlots()) { const FRenderTargetBindingSlots& RenderTargets = Parameter.GetAsRenderTargetBindingSlots(); RenderTargets.Enumerate([&](FRenderTargetBinding RenderTarget) { RenderTarget.GetTexture()->DebugData.bAllowRHIAccess = bAllowAccess; if (FRDGTextureRef ResolveTexture = RenderTarget.GetResolveTexture()) { ResolveTexture->DebugData.bAllowRHIAccess = bAllowAccess; } }); if (FRDGTextureRef Texture = RenderTargets.DepthStencil.GetTexture()) { Texture->DebugData.bAllowRHIAccess = bAllowAccess; } } }); } FRDGBarrierValidation::FRDGBarrierValidation(const FRDGPassRegistry* InPasses, const FRDGEventName& InGraphName) : Passes(InPasses) , GraphName(InGraphName.GetTCHAR()) { check(Passes); } void FRDGBarrierValidation::ValidateBarrierBatchBegin(const FRDGPass* Pass, const FRDGBarrierBatchBegin& Batch) { checkf(!Batch.IsTransitionValid() && !BatchMap.Contains(&Batch), TEXT("Begin barrier batch '%s' has already been submitted."), *Batch.GetName()); if (!GRDGTransitionLog) { return; } FResourceMap& ResourceMap = BatchMap.Emplace(&Batch); for (int32 Index = 0; Index < Batch.Transitions.Num(); ++Index) { FRDGParentResourceRef Resource = Batch.Resources[Index]; const FRHITransitionInfo& Transition = Batch.Transitions[Index]; if (Resource->Type == ERDGParentResourceType::Texture) { ResourceMap.Textures.FindOrAdd(static_cast(Resource)).Add(Transition); } else { check(Resource->Type == ERDGParentResourceType::Buffer); FRDGBufferRef Buffer = static_cast(Resource); checkf(!ResourceMap.Buffers.Contains(Buffer), TEXT("Buffer %s was added multiple times to batch %s."), Buffer->Name, *Batch.GetName()); ResourceMap.Buffers.Emplace(Buffer, Transition); } } const bool bAllowedForPass = IsDebugAllowedForGraph(GraphName) && IsDebugAllowedForPass(Pass->GetName()); // Debug mode will report errors regardless of logging filter. if (!bAllowedForPass && !GRDGDebug) { return; } bool bFoundFirst = false; const auto LogHeader = [&]() { if (!bFoundFirst) { bFoundFirst = true; UE_CLOG(bAllowedForPass, LogRDG, Display, TEXT("%s (Begin):"), *Batch.GetName()); } }; for (const auto& Pair : ResourceMap.Textures) { FRDGTextureRef Texture = Pair.Key; const bool bAllowedForResource = bAllowedForPass && IsDebugAllowedForResource(Texture->Name); const auto& Transitions = Pair.Value; if (bAllowedForResource && Transitions.Num()) { LogHeader(); UE_LOG(LogRDG, Display, TEXT("\t(%p) %s:"), Texture, Texture->Name); } const FRDGTextureSubresourceLayout SubresourceLayout = Texture->GetSubresourceLayout(); for (const FRHITransitionInfo& Transition : Transitions) { check(SubresourceLayout.GetSubresourceCount() > 0); EnumerateSubresources(Transition, SubresourceLayout.NumMips, SubresourceLayout.NumArraySlices, SubresourceLayout.NumPlaneSlices, [&](FRDGTextureSubresource Subresource) { const int32 SubresourceIndex = SubresourceLayout.GetSubresourceIndex(Subresource); UE_CLOG(bAllowedForResource, LogRDG, Display, TEXT("\t\tMip(%d), Array(%d), Slice(%d): %s -> %s"), Subresource.MipIndex, Subresource.ArraySlice, Subresource.PlaneSlice, *GetRHIAccessName(Transition.AccessBefore), *GetRHIAccessName(Transition.AccessAfter)); }); } } if (bAllowedForPass) { for (auto Pair : ResourceMap.Buffers) { FRDGBufferRef Buffer = Pair.Key; const FRHITransitionInfo& Transition = Pair.Value; if (!IsDebugAllowedForResource(Buffer->Name)) { continue; } LogHeader(); UE_LOG(LogRDG, Display, TEXT("\t(%p) %s: %s -> %s"), Buffer, Buffer->Name, *GetRHIAccessName(Transition.AccessBefore), *GetRHIAccessName(Transition.AccessAfter)); } } } void FRDGBarrierValidation::ValidateBarrierBatchEnd(const FRDGPass* Pass, const FRDGBarrierBatchEnd& Batch) { if (!GRDGTransitionLog || !IsDebugAllowedForGraph(GraphName) || !IsDebugAllowedForPass(Pass->GetName())) { return; } bool bFoundFirstBatch = false; for (const FRDGBarrierBatchBegin* Dependent : Batch.Dependencies) { // Transitions can be queued into multiple end batches. The first to get flushed nulls out the transition. if (!Dependent->IsTransitionValid()) { continue; } const FResourceMap& ResourceMap = BatchMap.FindChecked(Dependent); TArray Textures; if (ResourceMap.Textures.Num()) { ResourceMap.Textures.GetKeys(Textures); } TArray Buffers; if (ResourceMap.Buffers.Num()) { ResourceMap.Buffers.GetKeys(Buffers); } if (Textures.Num() || Buffers.Num()) { if (!bFoundFirstBatch) { UE_LOG(LogRDG, Display, TEXT("%s (End):"), *Batch.GetName()); bFoundFirstBatch = true; } } for (FRDGTextureRef Texture : Textures) { UE_LOG(LogRDG, Display, TEXT("\t(%p) %s"), Texture, Texture->Name); } for (FRDGBufferRef Buffer : Buffers) { UE_LOG(LogRDG, Display, TEXT("\t(%p) %s"), Buffer, Buffer->Name); } } } void FRDGBarrierValidation::ValidateExecuteEnd() { for (auto Pair : BatchMap) { checkf(!Pair.Key->IsTransitionValid(), TEXT("A batch was begun but never ended.")); } BatchMap.Empty(); } namespace { const TCHAR* RasterColorName = TEXT("#ff7070"); const TCHAR* ComputeColorName = TEXT("#70b8ff"); const TCHAR* AsyncComputeColorName = TEXT("#70ff99"); const TCHAR* CopyColorName = TEXT("#ffdb70"); const TCHAR* TextureColorAttributes = TEXT("color=\"#5800a1\", fontcolor=\"#5800a1\""); const TCHAR* BufferColorAttributes = TEXT("color=\"#007309\", fontcolor=\"#007309\""); const TCHAR* AliasColorAttributes = TEXT("color=\"#00ff00\", fontcolor=\"#00ff00\""); const TCHAR* GetPassColorName(ERDGPassFlags Flags) { if (EnumHasAnyFlags(Flags, ERDGPassFlags::Raster)) { return RasterColorName; } if (EnumHasAnyFlags(Flags, ERDGPassFlags::Compute)) { return ComputeColorName; } if (EnumHasAnyFlags(Flags, ERDGPassFlags::AsyncCompute)) { return AsyncComputeColorName; } if (EnumHasAnyFlags(Flags, ERDGPassFlags::Copy)) { return CopyColorName; } return TEXT("#ffffff"); } FString GetSubresourceStateLabel(FRDGSubresourceState State) { check(State.Pipeline == ERHIPipeline::Graphics || State.Pipeline == ERHIPipeline::AsyncCompute); const TCHAR* FontColor = State.Pipeline == ERHIPipeline::AsyncCompute ? AsyncComputeColorName : RasterColorName; return FString::Printf(TEXT("%s"), FontColor, *GetRHIAccessName(State.Access)); } } FString FRDGLogFile::GetProducerName(FRDGPassHandle PassHandle) { if (PassHandle.IsValid()) { return GetNodeName(PassHandle); } else { return GetNodeName(ProloguePassHandle); } } FString FRDGLogFile::GetConsumerName(FRDGPassHandle PassHandle) { if (PassHandle.IsValid()) { return GetNodeName(PassHandle); } else { return GetNodeName(EpiloguePassHandle); } } FString FRDGLogFile::GetNodeName(FRDGPassHandle PassHandle) { PassesReferenced.Add(PassHandle); return FString::Printf(TEXT("P%d"), PassHandle.GetIndex()); } FString FRDGLogFile::GetNodeName(const FRDGTexture* Texture) { return FString::Printf(TEXT("T%d"), Textures.AddUnique(Texture)); } FString FRDGLogFile::GetNodeName(const FRDGBuffer* Buffer) { return FString::Printf(TEXT("B%d"), Buffers.AddUnique(Buffer)); } void FRDGLogFile::AddLine(const FString& Line) { File += Indentation + Line + TEXT("\n"); } void FRDGLogFile::AddBraceBegin() { AddLine(TEXT("{")); Indentation += TEXT("\t"); } void FRDGLogFile::AddBraceEnd() { const bool bSuccess = Indentation.RemoveFromEnd(TEXT("\t")); check(bSuccess); AddLine(TEXT("}")); } void FRDGLogFile::Begin( const FRDGEventName& InGraphName, const FRDGPassRegistry* InPasses, FRDGPassBitArray InPassesCulled, FRDGPassHandle InProloguePassHandle, FRDGPassHandle InEpiloguePassHandle) { if (GRDGDumpGraph) { if (GRDGImmediateMode) { UE_LOG(LogRDG, Warning, TEXT("Dump graph (%d) requested, but immediate mode is enabled. Skipping."), GRDGDumpGraph); return; } check(File.IsEmpty()); check(InPasses && InEpiloguePassHandle.IsValid()); Passes = InPasses; PassesCulled = InPassesCulled; ProloguePassHandle = InProloguePassHandle; EpiloguePassHandle = InEpiloguePassHandle; GraphName = InGraphName.GetTCHAR(); if (GraphName.IsEmpty()) { const int32 UnknownGraphIndex = GRDGDumpGraphUnknownCount++; GraphName = FString::Printf(TEXT("Unknown%d"), UnknownGraphIndex); } AddLine(TEXT("digraph RDG")); AddBraceBegin(); AddLine(TEXT("rankdir=LR; labelloc=\"t\"")); bOpen = true; } } void FRDGLogFile::End() { if (!GRDGDumpGraph || !bOpen) { return; } TArray PassesGraphics; TArray PassesAsyncCompute; for (FRDGPassHandle PassHandle = Passes->Begin(); PassHandle != Passes->End(); ++PassHandle) { const FRDGPass* Pass = Passes->Get(PassHandle); const ERHIPipeline Pipeline = Pass->GetPipeline(); switch (Pipeline) { case ERHIPipeline::Graphics: PassesGraphics.Add(PassHandle); break; case ERHIPipeline::AsyncCompute: PassesAsyncCompute.Add(PassHandle); break; default: checkNoEntry(); } } if (GRDGDumpGraph == RDG_DUMP_GRAPH_TRACKS) { FRDGPassHandle PrevPassesByPipeline[uint32(ERHIPipeline::Num)]; for (FRDGPassHandle PassHandle = Passes->Begin(); PassHandle != Passes->End(); ++PassHandle) { const FRDGPass* Pass = Passes->Get(PassHandle); if (!EnumHasAnyFlags(Pass->GetFlags(), ERDGPassFlags::Copy | ERDGPassFlags::Raster | ERDGPassFlags::Compute | ERDGPassFlags::AsyncCompute)) { continue; } ERHIPipeline PassPipeline = Pass->GetPipeline(); checkf(FMath::IsPowerOfTwo(uint32(PassPipeline)), TEXT("This logic doesn't handle multi-pipe passes.")); uint32 PipeIndex = FMath::FloorLog2(uint32(PassPipeline)); FRDGPassHandle& PrevPassInPipelineHandle = PrevPassesByPipeline[PipeIndex]; if (PrevPassInPipelineHandle.IsValid()) { AddLine(FString::Printf(TEXT("\"%s\" -> \"%s\" [style=\"filled\", penwidth=2, color=\"%s\"]"), *GetNodeName(PrevPassInPipelineHandle), *GetNodeName(PassHandle), GetPassColorName(Pass->GetFlags()))); } if (Pass->GetPipeline() == ERHIPipeline::AsyncCompute) { const auto AddCrossPipelineEdge = [&](FRDGPassHandle PassBefore, FRDGPassHandle PassAfter) { AddLine(FString::Printf(TEXT("\"%s\" -> \"%s\" [penwidth=5, style=\"dashed\" color=\"#f003fc\"]"), *GetNodeName(PassBefore), *GetNodeName(PassAfter))); }; if (Pass->IsAsyncComputeBegin()) { AddCrossPipelineEdge(Pass->GetGraphicsForkPass(), PassHandle); } if (Pass->IsAsyncComputeEnd()) { AddCrossPipelineEdge(PassHandle, Pass->GetGraphicsJoinPass()); } } PrevPassInPipelineHandle = PassHandle; } } else if (GRDGDumpGraph == RDG_DUMP_GRAPH_PRODUCERS) { for (FRDGPassHandle PassHandle = Passes->Begin(); PassHandle != Passes->End(); ++PassHandle) { if (PassHandle == EpiloguePassHandle) { break; } const FRDGPass* Pass = Passes->Get(PassHandle); for (FRDGPassHandle ProducerHandle : Pass->GetProducers()) { if (ProducerHandle != ProloguePassHandle) { const FRDGPass* Producer = Passes->Get(ProducerHandle); File += FString::Printf(TEXT("\t\"%s\" -> \"%s\" [penwidth=2, color=\"%s:%s\"]\n"), *GetNodeName(ProducerHandle), *GetNodeName(PassHandle), GetPassColorName(Pass->GetFlags()), GetPassColorName(Producer->GetFlags())); } } } } AddLine(TEXT("subgraph Passes")); AddBraceBegin(); const auto AddPass = [&](FRDGPassHandle PassHandle) { if (!PassesReferenced.Contains(PassHandle)) { return; } const FRDGPass* Pass = Passes->Get(PassHandle); const TCHAR* Style = PassesCulled[PassHandle] ? TEXT("dashed") : TEXT("filled"); FString PassName = FString::Printf(TEXT("[%d]: %s"), PassHandle.GetIndex(), Pass->GetName()); if (Pass->GetParameters().HasExternalOutputs()) { PassName += TEXT("\n(Has External UAVs)"); } AddLine(FString::Printf(TEXT("\"%s\" [shape=box, style=%s, label=\"%s\", color=\"%s\"]"), *GetNodeName(PassHandle), Style, *PassName, GetPassColorName(Pass->GetFlags()))); }; { uint32 RenderTargetClusterCount = 0; for (FRDGPassHandle PassHandle : PassesGraphics) { const FRDGPass* Pass = Passes->Get(PassHandle); if (Pass->IsMergedRenderPassBegin()) { const uint32 RenderTargetClusterIndex = RenderTargetClusterCount++; AddLine(FString::Printf(TEXT("subgraph cluster_%d"), RenderTargetClusterIndex)); AddBraceBegin(); AddLine(TEXT("style=filled;color=\"#ffe0e0\";fontcolor=\"#aa0000\";label=\"Render Pass Merge\";fontsize=10")); } AddPass(PassHandle); if (Pass->IsMergedRenderPassEnd()) { AddBraceEnd(); } } } for (FRDGPassHandle PassHandle : PassesAsyncCompute) { AddPass(PassHandle); } AddBraceEnd(); AddLine(TEXT("subgraph Textures")); AddBraceBegin(); for (const FRDGTexture* Texture : Textures) { FString Line = FString::Printf(TEXT("\"%s\" [shape=oval, %s, label=\"%s"), *GetNodeName(Texture), TextureColorAttributes, Texture->Name); if (Texture->IsExternal()) { Line += TEXT("\n(External)"); } Line += TEXT("\"]"); AddLine(Line); } AddBraceEnd(); AddLine(TEXT("subgraph Buffers")); AddBraceBegin(); for (const FRDGBuffer* Buffer : Buffers) { FString Line = FString::Printf(TEXT("\"%s\" [shape=oval, %s, label=\"%s"), *GetNodeName(Buffer), BufferColorAttributes, Buffer->Name); if (Buffer->IsExternal()) { Line += TEXT("\n(External)"); } Line += TEXT("\"]"); AddLine(Line); } AddBraceEnd(); uint32 NumPassesActive = 0; uint32 NumPassesCulled = 0; for (FRDGPassHandle PassHandle = Passes->Begin(); PassHandle != Passes->End(); ++PassHandle) { if (PassesCulled[PassHandle]) { NumPassesCulled++; } else { NumPassesActive++; } } AddLine(FString::Printf(TEXT("label=\"%s [Active Passes: %d, Culled Passes: %d, Textures: %d, Buffers: %d]\""), *GraphName, NumPassesActive, NumPassesCulled, Textures.Num(), Buffers.Num())); AddBraceEnd(); check(Indentation.IsEmpty()); const TCHAR* DumpType = TEXT(""); switch (GRDGDumpGraph) { case RDG_DUMP_GRAPH_RESOURCES: DumpType = TEXT("_resources"); break; case RDG_DUMP_GRAPH_PRODUCERS: DumpType = TEXT("_producers"); break; case RDG_DUMP_GRAPH_TRACKS: DumpType = TEXT("_tracks"); break; } FFileHelper::SaveStringToFile(File, *(FPaths::ProjectLogDir() / FString::Printf(TEXT("RDG_%s%s.gv"), *GraphName, DumpType))); bOpen = false; } bool FRDGLogFile::IncludeTransitionEdgeInGraph(FRDGPassHandle Pass) const { return Pass.IsValid() && Pass != ProloguePassHandle && Pass != EpiloguePassHandle; } bool FRDGLogFile::IncludeTransitionEdgeInGraph(FRDGPassHandle PassBefore, FRDGPassHandle PassAfter) const { return IncludeTransitionEdgeInGraph(PassBefore) && IncludeTransitionEdgeInGraph(PassAfter) && PassBefore < PassAfter; } void FRDGLogFile::AddFirstEdge(const FRDGTextureRef Texture, FRDGPassHandle FirstPass) { if (GRDGDumpGraph == RDG_DUMP_GRAPH_RESOURCES && bOpen && IncludeTransitionEdgeInGraph(FirstPass)) { AddLine(FString::Printf(TEXT("\"%s\" -> \"%s\" [%s]"), *GetNodeName(Texture), *GetNodeName(FirstPass), TextureColorAttributes)); } } void FRDGLogFile::AddFirstEdge(const FRDGBufferRef Buffer, FRDGPassHandle FirstPass) { if (GRDGDumpGraph == RDG_DUMP_GRAPH_RESOURCES && bOpen && IncludeTransitionEdgeInGraph(FirstPass)) { AddLine(FString::Printf(TEXT("\"%s\" -> \"%s\" [%s]"), *GetNodeName(Buffer), *GetNodeName(FirstPass), BufferColorAttributes)); } } void FRDGLogFile::AddAliasEdge(const FRDGTextureRef TextureBefore, FRDGPassHandle BeforePass, const FRDGTextureRef TextureAfter, FRDGPassHandle AfterPass) { if (GRDGDumpGraph == RDG_DUMP_GRAPH_RESOURCES && bOpen && IncludeTransitionEdgeInGraph(BeforePass, AfterPass)) { AddLine(FString::Printf(TEXT("\"%s\" -> \"%s\" [%s, label=%s -> %s>]"), *GetProducerName(BeforePass), *GetConsumerName(AfterPass), AliasColorAttributes, TextureBefore->Name, TextureAfter->Name)); } } void FRDGLogFile::AddAliasEdge(const FRDGBufferRef BufferBefore, FRDGPassHandle BeforePass, const FRDGBufferRef BufferAfter, FRDGPassHandle AfterPass) { if (GRDGDumpGraph == RDG_DUMP_GRAPH_RESOURCES && bOpen && IncludeTransitionEdgeInGraph(BeforePass, AfterPass)) { AddLine(FString::Printf(TEXT("\"%s\" -> \"%s\" [%s, label=%s -> %s>]"), *GetProducerName(BeforePass), *GetConsumerName(AfterPass), AliasColorAttributes, BufferBefore->Name, BufferAfter->Name)); } } void FRDGLogFile::AddTransitionEdge(FRDGPassHandle PassHandle, FRDGSubresourceState StateBefore, FRDGSubresourceState StateAfter, const FRDGTextureRef Texture) { if (GRDGDumpGraph == RDG_DUMP_GRAPH_RESOURCES && bOpen && IncludeTransitionEdgeInGraph(StateBefore.FirstPass, PassHandle)) { if (FRDGSubresourceState::IsTransitionRequired(StateBefore, StateAfter)) { AddLine(FString::Printf(TEXT("\"%s\" -> \"%s\" [%s, label=<%s: %s -> %s>]"), *GetProducerName(StateBefore.LastPass), *GetConsumerName(StateAfter.FirstPass), TextureColorAttributes, Texture->Name, *GetSubresourceStateLabel(StateBefore), *GetSubresourceStateLabel(StateAfter))); } else { AddLine(FString::Printf(TEXT("\"%s\" -> \"%s\" [%s, label=<%s: %s>]"), *GetProducerName(StateBefore.FirstPass), *GetConsumerName(PassHandle), TextureColorAttributes, Texture->Name, *GetSubresourceStateLabel(StateBefore))); } } } void FRDGLogFile::AddTransitionEdge(FRDGPassHandle PassHandle, FRDGSubresourceState StateBefore, FRDGSubresourceState StateAfter, const FRDGTextureRef Texture, FRDGTextureSubresource Subresource) { if (GRDGDumpGraph == RDG_DUMP_GRAPH_RESOURCES && bOpen && IncludeTransitionEdgeInGraph(StateBefore.FirstPass, PassHandle)) { if (FRDGSubresourceState::IsTransitionRequired(StateBefore, StateAfter)) { AddLine(FString::Printf(TEXT("\"%s\" -> \"%s\" [%s, label=<%s[%d][%d][%d]: %s -> %s>]"), *GetProducerName(StateBefore.LastPass), *GetConsumerName(StateAfter.FirstPass), TextureColorAttributes, Texture->Name, Subresource.MipIndex, Subresource.ArraySlice, Subresource.PlaneSlice, *GetSubresourceStateLabel(StateBefore), *GetSubresourceStateLabel(StateAfter))); } else { AddLine(FString::Printf(TEXT("\"%s\" -> \"%s\" [%s, label=<%s[%d][%d][%d]: %s>]"), *GetProducerName(StateBefore.FirstPass), *GetConsumerName(PassHandle), TextureColorAttributes, Texture->Name, Subresource.MipIndex, Subresource.ArraySlice, Subresource.PlaneSlice, *GetSubresourceStateLabel(StateBefore))); } } } void FRDGLogFile::AddTransitionEdge(FRDGPassHandle PassHandle, FRDGSubresourceState StateBefore, FRDGSubresourceState StateAfter, const FRDGBufferRef Buffer) { if (GRDGDumpGraph == RDG_DUMP_GRAPH_RESOURCES && bOpen && IncludeTransitionEdgeInGraph(StateBefore.FirstPass, PassHandle)) { if (FRDGSubresourceState::IsTransitionRequired(StateBefore, StateAfter)) { AddLine(FString::Printf(TEXT("\"%s\" -> \"%s\" [%s, label=<%s: %s -> %s>]"), *GetProducerName(StateBefore.LastPass), *GetConsumerName(StateAfter.FirstPass), BufferColorAttributes, Buffer->Name, *GetSubresourceStateLabel(StateBefore), *GetSubresourceStateLabel(StateAfter))); } else { AddLine(FString::Printf(TEXT("\"%s\" -> \"%s\" [%s, label=<%s: %s>]"), *GetProducerName(StateBefore.FirstPass), *GetConsumerName(PassHandle), BufferColorAttributes, Buffer->Name, *GetSubresourceStateLabel(StateBefore))); } } } #endif